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Controversy over the new dietary guidelines

Yesterday I filmed a piece on Fox Business about the new dietary recommendations and the call to reduce meat consumption to improve health and the environment (I couldn't get the video to embed, but you can view it here).  I suppose I had at least a couple good points to make because the clip was featured for most of yesterday on the main web page for Fox News.  

One of the hosts mentioned a Cambridge study showing that vegetarians and vegans have substantially lower environmental impacts than meat-eating diets.  A written piece at foxnews.com about the recommendations also mentions the same study.  I'm not sure how representative that cited study is.  My own analysis suggests that vegetarians spend about the same amount on food as do meat eaters.  To the extent prices reflect resource use, that stat would suggest both diets are "using up" similar levels of "stuff."  I've also written on the argument that the grain fed to livestock is "wasted."

But, perhaps more importantly, what evidence is cited in the new report of the dietary guidelines committee?  The papers they cite seem to suggest small improvements in greenhouse gas (GHG) emissions and improved health outcomes (but more on that in a minute) from a move to vegetarian diet.  Here are some selected quotes of the review in Chapter 5 part D where quantitative impacts on environment were mentioned (note: there are many other cited studies, some of which suggest higher impacts).

“Peters et al. examined 42 different dietary patterns and land use in New York, with patterns ranging from low-fat, lacto-ovo vegetarian diets to high fat, meat-rich omnivorous diets . . . although meat increased land requirements, diets including meat could feed more people than some higher fat vegetarian-style diets”

and

“Aston et al. assessed a pattern that was modeled on a feasible UK population in which the proportion of vegetarians in the survey was doubled, and the remainder adopted a diet pattern consistent with the lowest category of red and processed meat (RPM) consumers. They found . . . the expected reduction in GHG for this diet was ~3 percent of current total carbon dioxide (CO2) emissions for agriculture. De Carvalho et al. also examined a high RPM dietary pattern with diet quality assessed using the Brazilian Healthy Eating Index.They found . . . that excessive meat intake was associated not only with poorer diet quality but also with increased projected GHG emissions (~ 4 percent total CO2 emitted by agriculture). ”

This one is most interesting references:

“a report from Heller and Keoleian suggests that an isocaloric shift from the average U.S. diet (at current U.S. per capita intake of 2,534 kcals/day from Loss-Adjusted Food Availability (LAFA) data) to a pattern that adheres to the 2010 Dietary Guidelines for Americans would result in a 12 percent increase in diet-related GHG emissions. This result was modified, however, by their finding that if Americans consumed the recommended pattern within the recommended calorie intake level of 2,000 kcal/day, there would be a 1 percent decrease in GHG emissions. ”

My take?  Eating too many calories likely has as much an impact on GHG as eating meat.  Reducing meat consumption would lower GHG emissions, but I would characterize the effects as "small" (3 to 4% of the GHG emissions from agriculture, or likely less than 1% of the total of all GHG emissions), particularly if people move toward pork and poultry, which have far fewer GHG emissions than ruminants like cattle.  Moreover, if we want to improve environmental impacts of livestock production, I think we're likely to get a bigger bang for our buck by improving productivity and researching new ways to reduce impacts than we will be cajoling people to eat less meat (see this paper on the reduction in environmental impact of beef production brought about over the past 40 years due to technological advancement).

What about the health impacts of meat consumption?  It is true that many observational, epidemiological studies show a correlation between red meat eating and adverse health outcomes (interestingly there is a fair amount of overlap on the authors of the dietary studies and the environmental studies on meat eating).  But, this is a pretty weak form of evidence, and much of this work reminds of the kinds of regression analyses done in the 1980s and 90s in economics before the so-called "credibility revolution." 

There have been many, many books written on the topic of whether meat eating is good or bad for you, and I won't try to adjudicate them all here.  However, I will point you to this really interesting exchange (see the comments section) on Marion Nestle's website where she mentions the new guidelines and takes a swipe at Nina Teicholz's book, Big Fat Surprise.  Nina responds, as do her critics.  

Food Labels - Environmental Edition

I had a recent request on Twitter asking for my thoughts on environmental labels for food.  The question seems to be motivated by recent discussions about the USDA and the Dept of Health and Human Services possibly incorporating environmental considerations into the federal dietary guidelines.  As I've previously noted, this move makes me a bit nervous because it entails non-scientific value judgments about how to integrate disparate issues (health and environment) into a single overall recommendation.  But, even as I said there: 

“It isn’t necessarily a bad idea for the government to convey the scientific evidence on the environmental impacts of producing different foods.”

Of course, that still leaves many unanswered questions.  What do we mean by environment?  Just C02, or is it water quality, or deforestation, or what?  Is the label voluntary or mandatory?  How will food companies respond to the label?  What do consumers understand about the label?  And so on.

In principle, it is possible to imagine something like a nutrition facts panel for environmental issues.  However, the two are not as analogous as might first appear.  First, scientists have a pretty good idea how to measure the fat, carb, and protein contents of food, whereas measuring C02 or deforestation impacts is tricky business with a lot of uncertainty.  Moreover, the nutritional content of a processed food is relatively stable regardless of where the raw ingredients came from, which plant or facility was used to manufacture it, how it got to the store, or how you transported and cooked it.  None of this would be true for an environmental label, which would require more more extensive (and more costly) monitoring and tracing, and if it is at all accurate, one could have two Wheaties boxes that are nutritionally equivalent but with very different environmental impacts.  That may be all the more reason to inform consumers, but the point I'm trying to emphasize here is the much higher cost and greater uncertainty in informing about nutrition vs the environment.  

Finally, an perhaps most importantly, nutritional outcomes are, by and large, what we economists would call "private goods."  The nutrient contents of the foods I eat affect me personally and not others (let's put aside Medicare/Medicare, which is another issue I've touched on here, here, here, and here).  In these cases, the effects of a label on my choices, and ultimate welfare consequences are more straightforward.  Let's compare that to environmental labels, which signal attributes associated with public goods and possible externalities, where we suspect there are likely to be problems with coordination, free riding, etc.  I suspect most economists would tend to look toward getting the property rights or the prices right as the "solutions" in these cases rather than looking toward labels (here's a paper I wrote on that issue).

Finally, I'll note there is a long literature in agricultural economics on food labels - focusing on when and under what conditions labels enhance social welfare.  The results of this literature are hard to summarize (meaning the effects are complex).  Here are a few good places to start if you're interested in the topic.

My answer to the question: should food products contain environmental labels?  I don't know.  There are far too many unanswered questions to say anything more precise than that.

Impacts of Dietary Recommendations

Following the government's dietary recommendations may lead to . . . climate change?

New research suggests the following:

“if Americans adopted the recommendations in USDA’s “Dietary Guidelines for Americans, 2010,” while keeping caloric intake constant, diet-related greenhouse gas emissions would increase 12 percent.”

Rather than trying to anticipate the unintended consequences of such recommendations, the study authors want to add another layer on top of the nutritional recommendations

“The take-home message is that health and environmental agendas are not aligned in the current dietary recommendations,” Heller said.

The paper’s findings are especially relevant now because the USDA Dietary Guidelines Advisory Committee is for the first time considering food sustainability within the context of dietary recommendations, he said.”

As I've pointed out before, trying to integrate nutritional and environmental objectives into recommendations involves value judgement that go beyond scientific evidence. Moreover, focusing just on C02 emissions or nutritional composition (as if that's easy to characterize) ignores many other factors.  On a per-acre basis, which crops are the biggest users of pesticides or water? You might be surprised to find out that it is not corn, soybeans, or wheat but rather many fruits and veggies like lemons, strawberries, etc. 

Rather than trying to add layer upon layer to the dietary recommendations, why not respect people's choices?  The price of food reflects the resources used and the demands on those resources.  If the problem is that prices don't fully reflect water use or C02 emissions, then the idea is to think about assigning property rights in a way that that information-aggregating markets help allocate those resources.  But, I suppose it's less fun to let markets allocate resources.  That would take away our power to tell others what to eat.  

Buffalo extermination - environmental catastrophe or savior?

Given my Wall Street Journal article earlier this week, I've received a large number of questions and comment about beef cattle production and the environment.  One comment on the piece in the WSJ made an observation that had never occurred to me.

One of the big concerns with beef production is methane emissions.  Methane is a more potent greenhouse gas than carbon.  Cattle are ruminants, and their digestion produces methane (which is released not from the back-end of the cow as is typically asserted but rather the front-end).  

In any event, it seems a common presumption of many who are worried about this issue is that if we got rid of all the beef cattle in the US (or at least drastically reduced their numbers), that would be a great thing because we could significantly cut greenhouse gas emissions and help curb climate change.

In fact, we did something very much like that in the US in the mid to late 1800s, and it is almost universally considered a tragedy.

According to some environmental groups, there was once more than 20 million bison roaming the Great Plains.  This number may not be far fetched.  According to one academic paper, the bison carrying capacity of the Great Plains in 1860 was estimated between 13.78 to 20.67 million bison.   According to EPA calculations, American bison generate as much or more methane as do beef cattle on a per-head basis (compare table A-184 to A-187).  

In 1990, there were only about 50,000 head of bison in the US.  Today there are less than 200,000.  Thus, there has been a 100 fold reduction in bison numbers since the mid 1800s.

Were these bison causing climate change back in the 1800s?  Is it a great victory for the environment that they were almost eradicated?    

Logically consistency would seem to dictate that we think about the methane emissions of the ~20 million American bison in the 1800s the same way we think about the methane emissions of the ~29 million beef cattle in the US today.   I suspect the total amount of methane emissions from 1860s bison population and 2014 US beef cattle population are roughly similar (according to the EPA, feedlot beef cattle have much lower per-head methane emissions than bison - about half as much).  [addendum: a reader subsequently emailed me and correctly pointed out that, including dairy cattle, there are actually more than 90 million cattle in the US today - a figure roughly 3 to 4 times more than the number of bison existing in the 1800s]

So, bison depopulation - environmental boon or ecological travesty?  Neither?  Both?